The Human Population: Growth & Distribution © Brooks/Cole Publishing Company / ITP

The Human Population:Growth & Distribution

© Brooks/Cole Publishing Company / ITP

Milestones

1850

1927

1960

1974

1987

1999

2011

Human Population Size: Early ThoughtsHuman Population Size: Early Thoughts

• Thomas Malthus– Predicted that population would

outrun food supply– Leading to decrease in food per

person • based on the idea that population if

unchecked increases at a geometric rate (i.e. 2, 4, 8, 16, etc.)

• food supply grows at an arithmetic rate (i.e. 1, 2, 3, 4, etc.)

• Thomas Malthus– Predicted that population would

outrun food supply– Leading to decrease in food per

person • based on the idea that population if

unchecked increases at a geometric rate (i.e. 2, 4, 8, 16, etc.)

• food supply grows at an arithmetic rate (i.e. 1, 2, 3, 4, etc.)

http://www.nndb.com/people/250/000024178/

What is Earth’s carrying capacity?

Some people say we have surpassed it (2 billion)

Others say we haven’t even come close (30 billion)

What is the ecological definition

of carrying capacity?

Population growth: Exponential or Logistic?

Fig.1–1

Present day (data is current from the US Census Bureau and their International Programs division)

•World Population Size: 7 billion

•World Growth Rate: 1.4%, ~84 million/year

•U.S. Population Size: 310 million


•birth rate and death rate reported as the number per thousand people;

•zero population growth (ZPG) occurs when births balance deaths

Population Size (N)

Population

Change

Births+

Immigration

Deaths+

Emigration

–=


Important VocabularyImportant VocabularyCrude birth rate (CBR)= the number of births per 1,000 individuals per year.

Crude death rate (CDR)= the number of deaths per 1,000 individuals per year.

Crude birth rate (CBR)= the number of births per 1,000 individuals per year.

Crude death rate (CDR)= the number of deaths per 1,000 individuals per year.Total fertility rate- an estimate of the average number of children that each woman in a population will bear.

Replacement level fertility- the total fertility rate required to offset the average number of deaths in a population and for the current population size to remain stable.

Total fertility rate- an estimate of the average number of children that each woman in a population will bear.

Replacement level fertility- the total fertility rate required to offset the average number of deaths in a population and for the current population size to remain stable.

Life expectancy- the average number of years that an infant born in a particular year in a particular country can be expected to live, given the current average life span and death rate of that country.

Life expectancy- the average number of years that an infant born in a particular year in a particular country can be expected to live, given the current average life span and death rate of that country.

Infant mortality rate- the number of deaths of children under 1 year of age per 1,000 live births.

Child mortality rate- the number of deaths of children under age 5 per 1,000 live births.

Infant mortality rate- the number of deaths of children under 1 year of age per 1,000 live births.

Child mortality rate- the number of deaths of children under age 5 per 1,000 live births.

Calculating percent growth rates

Calculating percent growth rates

If given crude rates:Global population growth rate = (CBR- CDR)/ 10

Natl. pop. growth rate = (CBR+ immigration) - (CDR + emigration)/ 10

If given raw values for inputs and outputs:Global population growth rate =[(Births-Deaths)/population size] x

100

Natl. pop. growth rate = (births+immigration)-(deaths+ emigration) X 100

population size

If given crude rates:Global population growth rate = (CBR- CDR)/ 10

Natl. pop. growth rate = (CBR+ immigration) - (CDR + emigration)/ 10

If given raw values for inputs and outputs:Global population growth rate =[(Births-Deaths)/population size] x

100

Natl. pop. growth rate = (births+immigration)-(deaths+ emigration) X 100

population size

Doubling TimeDoubling Time

Calculate with the Rule of 7070/growth rate % = doubling time in years

– If the population of a country grows at a rate of approximately 8% per year, the number of years required for the population to double is…?

Calculate with the Rule of 7070/growth rate % = doubling time in years

– If the population of a country grows at a rate of approximately 8% per year, the number of years required for the population to double is…?

8.75

Age Structure Diagrams

Proportion of the population in groupings of 5 years.

We can also look collectively at age classes.

•prereproductive (0–14 years)

•reproductive (15–44 years)

•postreproductive (45 & up)

•What info can we gain from looking at these groupings?


Age Structure diagrams

Fig. 9–11 © Brooks/Cole Publishing Company / ITP

• Expansive/rapid growth– Birth rate exceeds death rate– Pyramid shaped

• Expansive/rapid growth– Birth rate exceeds death rate– Pyramid shaped

Slow/Zero vs. Negative Growth


• Graying– Portion of elderly is increasing in developed countries

• Graying– Portion of elderly is increasing in developed countries

Fig.11–12b

Projections


Population Momentum

Continued population increase because of pre-reproductive individuals

entering reproductive age.

© Brooks/Cole Publishing Company / ITPFig. 9–11

Demographic Transitions


As a country transitions from a subsistence economy to industrialization and increased wealth, it

undergoes a predictable pattern of population shifts.

Demographic Transitions


Stage 1: Slow/no growth as CBR and CDR are equal.

Stage 2: Rapid growth. CBR remains high, while CDR declines.

Stage 3: Growth stabilizes as both CBR and CDR decrease. This is due to increased wealth and education.

Stage 4: Negative growth. Stable CDR but declining CBR.

Factors affecting pop. growth ratesFactors affecting pop. growth rates

• Population stage• Death rate• Birth rate

• TFR• Poverty & affluence

• Population stage• Death rate• Birth rate

• TFR• Poverty & affluence

CDRCDR• Trend over time?• Factors that cause this trend?

• Trend over time?• Factors that cause this trend?• Improved:– Medical care– Sanitation– Personal hygiene– Water supply– Nutrition– Agriculture/food production

• Improved:– Medical care– Sanitation– Personal hygiene– Water supply– Nutrition– Agriculture/food production

– Food preservation– Prenatal and/or neonatal care

– Food preservation– Prenatal and/or neonatal care

CBRCBR

Reasons for high birth rates pre- and early transition stage:

Reasons for high birth rates pre- and early transition stage:

• What is the trend over time?• Same as death rate?

• What is the trend over time?• Same as death rate?

– Compensate for high IMR

– Assure care for aging parents

– Provide a labor force– Cultural/religious practices

– Compensate for high IMR

– Assure care for aging parents

– Provide a labor force– Cultural/religious practices

– Lack of contraceptives

– Lack of family planning education

– Lack of women’s rights

– Lack of contraceptives

– Lack of family planning education

– Lack of women’s rights

– Need time to change• Cultural/religious practices

– Changing status of women is often slow to be accepted

– Educational & job opportunities for women take a long time to develop

– Slow advances in birth control production

– Slow implementation of elderly support infrastructure (ie s.s., health care, pensions)

– Need time to change• Cultural/religious practices

– Changing status of women is often slow to be accepted

– Educational & job opportunities for women take a long time to develop

– Slow advances in birth control production

– Slow implementation of elderly support infrastructure (ie s.s., health care, pensions)

Reasons for slower decrease in birth rates (compared to death rates) during transition stage:

Reasons for slower decrease in birth rates (compared to death rates) during transition stage:

TFRTFR• Global trend is a decrease• Global trend is a decrease

CausesCauses EffectsEffects• Increased & improved family planning

• Increased & improved family planning

• Fewer pregnancies, choice of family size

• Fewer pregnancies, choice of family size

• Increased education & job opportunities for women

• Increased education & job opportunities for women

• Delay having children, choose to have fewer children

• Delay having children, choose to have fewer children

• More industrialization / less subsistence agriculture

• More industrialization / less subsistence agriculture

• Fewer children needed for labor on family farms

• Fewer children needed for labor on family farms

more on TFRmore on TFR

CausesCauses EffectsEffects• Improved health care/ lower IMR

• Improved health care/ lower IMR

• More children likely to survive to adulthood

• More children likely to survive to adulthood

• People marry later in life

• People marry later in life

• Delayed childbearing leads to fewer children

• Delayed childbearing leads to fewer children

• Increased cost of raising a child

• Increased cost of raising a child

• Fewer children per family due to increased cost of living and education

• Fewer children per family due to increased cost of living and education

Affects of poverty & affluence on TFR Affects of poverty & affluence on TFR

FactorsFactors Reasons & EffectsReasons & Effects

• Higher IMR in developing countries

• Higher IMR in developing countries

• Poverty causes shortage of prenatal and pediatric care

• Have many children to ensure survival of some into adulthood

• Poverty causes shortage of prenatal and pediatric care

• Have many children to ensure survival of some into adulthood

• Developing countries are still in a transitional stage (agriculture is important)

• Developing countries are still in a transitional stage (agriculture is important)

• More children are needed for farm labor

• More children are needed for farm labor

TFR is much higher in developing countries than in developed countries. Why?

TFR is much higher in developing countries than in developed countries. Why?

Cont.’d Cont.’d


• Widespread poverty in developing countries

• Widespread poverty in developing countries

• Contraceptives are not affordable

• Contraceptives are not affordable

• Lack of education and employment opportunities for women in developing countries

• Lack of education and employment opportunities for women in developing countries

• Lower social status of women leads them to marry and bear children at young ages

• Lower social status of women leads them to marry and bear children at young ages

• Many developing countries have a societal preference for male children

• Many developing countries have a societal preference for male children

• Large families result from trying to bear as many sons as possible

• Large families result from trying to bear as many sons as possible

Cont.’d Cont.’d


• Cost of raising a child in a developed country is much higher

• Cost of raising a child in a developed country is much higher

• People choose to have fewer children to maintain a higher quality of life

• People choose to have fewer children to maintain a higher quality of life

• Women in developing nations often have low social status

• Women in developing nations often have low social status

• Women have no control over their own fertility

• Women have no control over their own fertility

• Developing countries tend to lack education about family planning

• Developing countries tend to lack education about family planning

• Less ability to control fertility

• Less ability to control fertility

Government control of population Government control of population Overpopulation reduces quality of lifeOverpopulation reduces quality of life

Incentives to reduce population growth: Incentives to reduce population growth:

• Free or subsidized family planning – eg. contraceptives, education about contraceptives

• Free or subsidized family planning – eg. contraceptives, education about contraceptives

• Economic rewards or penalties, eg – payment for sterilization,– tax deductions for 0-1 children only, – free health care & or education for 0-1 children families,– education and jobs for mothers of 1 child– taxes on additional children,– China specific: monthly subsidy, job priority given to only children, housing preferences, additional food rations, monetary compensation

• Economic rewards or penalties, eg – payment for sterilization,– tax deductions for 0-1 children only, – free health care & or education for 0-1 children families,– education and jobs for mothers of 1 child– taxes on additional children,– China specific: monthly subsidy, job priority given to only children, housing preferences, additional food rations, monetary compensation

Government control of population Government control of population Examples of how incentives might work: Examples of how incentives might work:

– Free health care would lead to lower infant and child mortality– Lower cost of living allows for higher quality of life

– Free health care would lead to lower infant and child mortality– Lower cost of living allows for higher quality of life

There may be drawbacks to incentive programs:

There may be drawbacks to incentive programs:

– Cultural/social/religious resistance – Cultural/social/religious resistance

– Children punished for parent choices – Children punished for parent choices – Infringement on human rights – Infringement on human rights

– Reduced tax revenues – Reduced tax revenues

– Increased child abandonment– Increased child abandonment

– In-utero gender discrimination – In-utero gender discrimination

Case Studies


U.S.

Fig. 9–16

•fertility near replacement rate;•continued population increase because of population momentum & immigration.


India

•1952 first national family planning program;•program disappointing;•fertility still 3.5.


China

•since 1970 efforts to better feed people & control population growth;•strict population control measures prevent couples from having more than one child;•Penalize couples who have more than one or two children

•Couples pledge to have no more than one child receive benefits

•although considered coercive, the policy is significantly slowing population growth.


Looking at all three…Looking at all three…• China is predicted to level off then start slowly decreasing

• India is predicted to continued to increase

• US is predicted to slowly continue to increase.

• China is predicted to level off then start slowly decreasing

• India is predicted to continued to increase

• US is predicted to slowly continue to increase.

Environmental impacts of population growth

Environmental impacts of population growth

Decreases in biodiversity due to:Decreases in biodiversity due to:

•Deforestation for agriculture, housing, fuel, mining •Deforestation for agriculture, housing, fuel, mining

•Fossil fuel burning releases greenhouse gases altering climate •Fossil fuel burning releases greenhouse gases altering climate

•Sulfur pollution from coal mining and burning leads to acidification of aquatic systems and terrestrial soils

•Sulfur pollution from coal mining and burning leads to acidification of aquatic systems and terrestrial soils •Overfishing reduces fish populations •Overfishing reduces fish populations

Human Carrying Capacity?


Fig. 9–18

Computer Models

•overshoot & collapse theoretically can be avoided;

•requires fertility at or below replacement level.


Ecological FootprintsEcological Footprints

• Estimate of TOTAL environmental impact of individuals

• Developed nations have large FP due to consumption of nonrenewable resources

• Impact= Population x Affluence x Technology

Check out your ecological footprint at www.myfootprint.org

• Estimate of TOTAL environmental impact of individuals

• Developed nations have large FP due to consumption of nonrenewable resources

• Impact= Population x Affluence x Technology

Check out your ecological footprint at www.myfootprint.org

Ecological FootprintEcological Footprint30.2

15.6

6.4

3.7

3.2

2.6

USA

Germany

Brazil

Indonesia

Nigeria

India

Amount of land required to support an individual at standard of living of population

20 4 6 8 1210 14 16 18 20 22 24 26 28 30 32 34Acres

over-population or over-consumption?over-population or over-consumption?

If everyone globally lived the ave. lifestyle of…If everyone globally lived the ave. lifestyle of…

• Democratic Rep. of the Congo (1.2)• China (1.8)• Japan (6)• India (1.1)• United Arab Emirates (16)• Afghanistan (0.62)• Australia (8.5)• Latvia (3.7)• France (7.3)• Brazil (2.6)• Mexico (2.7)• Canada (7.7)• United States (12.2)• Our class

• Democratic Rep. of the Congo (1.2)• China (1.8)• Japan (6)• India (1.1)• United Arab Emirates (16)• Afghanistan (0.62)• Australia (8.5)• Latvia (3.7)• France (7.3)• Brazil (2.6)• Mexico (2.7)• Canada (7.7)• United States (12.2)• Our class

…we would need this many Earths…we would need

this many Earths

[7 billion X hectares per capita]/10.8 billion= # of earths

Documents

The Human Population: Growth & Distribution © Brooks/Cole Publishing Company / ITP